The mineralization of calcium phosphate phases will be studied under highly reproducible conditions by the addition of well-characterized seed material to stable supersaturated solutions of calcium phosphate both at physiological pH and at pH levels typical of those leading to the formation of carious lesions. Reactions will be followed by monitoring the ionic concentrations in the supersaturated solutions and by studying the solid phases formed using x-ray diffraction, specific surface area, optical and electron microscopy. In addition, dissolution kinetic experiments will be used to determine the nature of the surface phases formed at various stages of the crystallization reactions. Studies will be made with synthetic calcium phosphate preparations, enamel, dentine and predentine as seed material. The effects of ions such as fluoride, polyphosphates, and phosphonates will be investigated. The kinetics of mineralization and demineralization of fluorapatite will be studied in order to elucidate its relationship with the corresponding HAP and enamel processes. This will be expected to yield useful information about the mechanism of topical fluoride treatments. Studies will also be made under conditions simulating those for plaque and calculus formation. BIBLIOGRAPHIC REFERENCES: The Growth of Calcium Phosphates on Natural Enamel. B. Tomazic, M. Tomson, and G.H. Nancollas, Calc. Tiss. Res., 19, 263 (1976). The Kinetics of Crystal Growth and Dissolution of Calcium and Magnesium Fluoride. G.L. Gardner and G.H. Nancollas, J. Dent. Res., 55, 342 (1976).